'Tinder is to the twenty-first century what the Pill was to the twentieth.' A friend just shared that pearl with me, and while it may be an exaggeration, there is no doubt that the app makes all manner of intercourse easier, and perhaps a little safer. The app works by presenting you with Facebook-sourced snapshots of one man (or woman) after another— all located somewhere in your vicinity—and if one of your chosen chooses you, it's a match! That happens more than 10,000,000 times a day, according to the company, and it's then that the texting can begin. (As for the sort-of-safe part, Tinder shows you which Facebook friends, if any, you share with a guy.)

The reasons why women use the app, and the types of relationships that develop out of it, are as varied as the human race itself (or the operating system in Her). Read on for the sexy, chaste, exhilarating, hilarious—and hilariously horrible—details.

CASE STUDY 1:

She Checked Off Every Item on Her Sexual Bucket List

She's barefoot, without makeup, and in a teeny black negligee when the elevator opens and I step out into her loft. "Hi!" she says cheerfully, reaching up to wrap me in a hug, before "Oh, you're so pretty!" tumbles out, almost as if she didn't mean to say it out loud. I blush. I'm not sure if she's just trying to make me feel at ease, but I'll take the compliment: It seems an excellent way to start a threesome.

Over the next few hours, after some strong weed, innocuous conversation, and repeat listens of Rhye's Woman, I'll have one of the most thrilling experiences of my life. Her boyfriend will kiss me, then she'll pull me onto her living-room floor, and I'll stare hazily at the ceiling, thinking, I can't believe this is happening.

A few weeks before, early in 2014, I'd connected with the male half of this pair over Tinder. A dirty blond with a boyish face, he wasn't my usual physical type, but when he asked after a brief introductory exchange, "Have you ever wanted to be with a couple?" it didn't feel creepy, because via Tinder, I could tell he knew 18 of my "friends," including the real ones, like my best girlfriend and a former friend with benefits, whose benefits I'd enjoyed for nine months. "Actually," I typed back, "that's on my sexual bucket list."

Some context: As a whole, 2013 had been an emotionally exhausting roller coaster of romantic disappointments. I'd had multiple mini relationships, but much to my clichéd, ever-so-slightly-panicky midthirties dismay, none had gained traction. Enough already, I decided after a head-clearing vacation over the holidays. I needed to do something different. This is often when a woman declares to her best girlfriends and to "the universe" that she's going on a man fast, abstaining from dating and sex to "heal." But more time alone felt like the last thing I needed. I mean, dear God, I've been alone for years. So instead of a man fast... how about a man gorge (spiked with a few representatives of my own sex), designed to check some items off the list? Because despite how loving, and lovely, my boyfriends have been over the years, they've often seemed intimidated by my experimental leanings. I had stuff to experience.

Which is how I found myself in the aforementioned threesome; being bossed around by a JFK Jr. look-alike; interviewing other group-sex candidates in East Village bars; and discovering my personal fine line between super hot and super skeevy dirty talk. I was happily more submissive than I've ever been, although I did find out that I really don't care to be slapped in the face. I buzzed the apartments of men I'd met only electronically who were skilled in orgasmic meditation, a kind of mindfulness practice in which the man strokes the woman in 15-minute intervals to increase awareness and connection, not to mention to extend pleasure. (I'd learned about OM years ago through a friend. My review based on four sessions: more clinical than sensual—although, I have to admit, one had been borderline transcendent.) Because I'm clueless about online porn, I actually had to ask a male friend how to cut and paste porn clips so that I could better sext with a guy who'd requested details about what turns me on—something no boyfriend had ever done. (A word about methods: I didn't announce the bucket list on Tinder—too many crazies out there. I revealed my intentions only once I communicated with someone for a while and decided I could trust him.)

"Why do you want to do these things with strangers?" a platonic friend asked me. I could hear the genuine confusion in his voice, but he's lucky enough to be in a relationship with someone who shares his carnal tastes and quirks. Perhaps someday I'll find the perfect combination of meaningful and mind-blowing—the dream, obviously—but not thus far. And regardless, I'm way too jealous to explore group sex with an actual boyfriend. (I was so conscious of this, in fact, that during that first threesome, I kept worrying that the dirty blond was going to neglect his girlfriend. "Wait, you shouldn't come with me!" I panted to him. "Shouldn't we stop so you can switch?" They both started laughing.) Plus, the almost-anonymity of these encounters certainly turns up the heat a notch.

When I first launched my project—and that's what it felt like—I had a pretty clear idea of things I wanted to try. But as I started sharing fantasies with my (very, very small) handful of similarly interested Tinder partners, my sexual world expanded even more: Did I want to have a threesome with two men? Well, actually, yes! How about two couples? I hadn't really thought about it, but...I'll try it! What about double penetration? No, thanks—that looks terrifying and way too porny.

Many of these scenarios did not end up happening (yet?), although not from lack of effort: My main partner in sexual experimentation created a flattering and well-written Craigslist Casual Encounters ad to recruit a second man, but none of the replies were workable. Disappointing, but not a big deal. For the first time in my life, my libido and interests were accepted, appreciated, and encouraged rather than feared or scorned. I learned more about what I wanted and didn't want, what felt good and what didn't.

After a few months, my connections started to wane. Couples are involved in their own lives; everyone is busy with work (at least in New York); and sometimes you just don't want to keep things going (the face slapper and I decided our, um, lifestyles were too different). And sexual questing brings its own form of exhaustion—all the planning, the meeting up, the issue of chemistry. After a multi-month period of having a hyperactive sex drive, I'm actually feeling more focused on work (yawn) these days, so I'm setting aside the bucket list. But...did you hear about that new threesome app, 3nder? I signed up.—Anonymous

CASE STUDY 2:

She Found the One

I'd been on every imaginable dating website and found nothing. I'm 36, I was going to leave New York City. Done. And then I was at the U.S. Open for work and my 22-year-old assistant was like, "Look around you! There are so many hot men. And you can find all of them on Tinder." So I got on, right there. It was the semifinals, but I didn't watch any tennis. I just flipped through pictures.

I went on a few dates and then I saw this guy on Tinder, 42, really good-looking. We started talking through the app, and that was going well, so he sent me his number, and it had an Orlando area code. Frankly, I did not want to meet up with a stranger who lived in a different city, but I agreed to a drink. We ended up barhopping, got a big Italian dinner at midnight, and talked the entire time. He walked me back to my house, we kissed on the street, I put him into a cab, and then I immediately started crying. I had finally met this amazing man, and he didn't live here. But the next morning I woke up to a text from him saying he wanted to see me again before he left. After that we started talking every single day; three weeks later I was on a plane to Orlando, and six months later we're moving in together.

Tinder can definitely lend itself to quick hookups, but what people don't realize is that it cuts through so much of the bullshit. It's conversational. It's text message. So it's authentic in ways those precrafted statements can never be. I've spent so much time weeding people out through ridiculous online conversations—when I think about the hours I've wasted.... But now I'm like, you know what? Everything happens for a reason. I'm sitting here looking at my pool in the backyard. Life is okay.—As told to Molly Langmuir

I'd thought about joining Tinder for months but just couldn't find the right photo to post. It had been two years and 75 pounds since I'd last had sex, and my agony about picking a selfie was a kind of synecdoche for how I felt about my body, dating, and mating in general.

I'd been the kind of fat girl who hoped that no one would really notice her 250 pounds, wouldn't notice even when she got naked. Or if a boy did notice, I hoped he'd have the civility not to mention it. No such luck. My two last suppers, so to speak, had been in the summer of 2011, and one of the guys, a neighbor with whom I'd been casually cavorting, volunteered, apropos of nothing, that while he knew I was self-conscious about my body, he thought I was beautiful. Thanks. I deleted his number from my phone. As for the other, I was sitting on top of him—we were good friends and had been sleeping together off and on since college—when he began massaging my rather large belly. The revulsion I felt is hard to quantify, and it got worse afterward. "I can't believe I was so turned on by that," he told me. Even if I had serious qualms about my weight, sex with this guy I adored and trusted had always made me feel like a goddess. Now it seemed like I should feel eternally grateful for managing to turn him on despite my fat self.

Before I lost the weight, I'd styled myself as a sexual adventuress, but I was really just a sexual supplicant, overcompensating for my size. A guy could degrade me; he could get himself off and ignore me—hey, it was the least I could do. Which isn't to say that I didn't enjoy myself, at times—I do believe there's a time and a place for everything in bed—but always having to be on, to be up for fulfilling my partner's every whim, was a burden that only underlined my self-hatred.

So, strangely enough, it was through Tinder that I learned to have vanilla sex. The frigid Friday night after I joined, I was listening to Joni Mitchell in my pajamas while messaging back and forth with a guy whose name was Sean or maybe Eric. He lived a mile away. "You should invite me over," he wrote. "Are you an ax murderer?" I asked. That turned into a conversation about the literary merits of American Psycho. I gave him my address.

I didn't bother to change out of my pajamas or even brush my teeth in preparation. He brought wine and homemade gluten-free muffins and wasn't just cute but genuinely smart and funny. After we talked about books and French movies for a bit, I asked him if he wanted to go upstairs and see my roof, which conveniently opened up to my bedroom. We sat on my bed, we kissed, and we ended up having sex.

It was sweet and slightly fumbling—it was missionary sex on my bed, nothing creative. But I felt like running outside and high-fiving anyone who passed, so relieved was I to finally be sexually active again.

I reveled in my new body. When he started kissing his way down my chest and stomach, I didn't grimace and panic about the mounds of flesh he was coming face to face with, nor try to shift my position or maneuver bits of clothing to artfully hide the "worst" parts. And my thighs were firm to his touch, my calves, wrapped around his back, defined. (The thousands of dollars in SoulCycle classes had paid off!) For the first time in memory, I was focused on my pleasure and not thinking two steps ahead about how I could heighten his so that he wouldn't remember me as the fat girl. In fact, I didn't think about his opinion much at all. I stayed in the moment.

The next morning I ate his muffins and sent him my number in case he wanted to see me again, but he never responded. This isn't a story about heart-break or rejection, however. I Tindered on, making out with budding DJs, sleeping with a guy who worked in reality television, kissing tattooed sales reps. My interest in them varied, but one thing was constant: My body was now normal enough to be unremarkable. Remarkable.—Anonymous

CASE STUDY 4:

She Knows From Bad Dates

His tagline was "I don't want no savior, baby. I just want to have a good time," so I should have known I wouldn't. But my rule of thumb is that if a man on Tinder actually asks me on a date and then follows up to confirm it (which happens maybe one out of 100 times when you match), I say yes. We agree to meet in the East Village at 10 P.M.—sketchy late, another bad sign. He texts me beforehand to say he's checked out my Facebook profile and thinks I'm hotter than he originally thought. Is that a compliment? I say I don't cheat by Facebooking, but I do scroll his Twitter feed, which is full of gems such as: "The reason Tinder will never work like a Grindr for straight people, the way it's supposed to, is because of women." Then he asks me how tall I am. I start to feel like a sex-toy doll, but I'm curious enough about how I'll handle him to show up.

Him: Tall, as advertised, but more techie than rocker in person; he can't carry off his knuckle tattoos and thick silver rings, never mind those earrings that stretch the lobes. We go inside the sushi place he's chosen. He immediately knocks his beer into my lap. In lieu of an apology, he tells me he cofounded Bang With Friends, an app for arranging purely sexual hookups (and which recently changed its name to Down). This explains his tweets, I think. (Oh, and when I later checked, I couldn't find his name associated with Bang or Down, so he's a liar, too!) Then he asks me why I'm single. I want to leave/die. What's worse, the place is cash only, and he doesn't have enough. I pay for our beers and his Philadelphia rolls.

He's decided we'll go to another bar. For reasons I can't entirely explain, I agree to this plan. He tries to hold my hand somewhere along Avenue A and spits into the street once...and again, and again. He explains he quit smoking ("disgusting habit"), and this is a side effect, but I don't mind, do I? Uncharacteristically, I tell the unvarnished truth: "Actually, I do." It doesn't register. He baby-talks to every dog we meet and keeps spitting.

When we get to the bar, he asks if he can kiss me. I shake my head no and down my beer so fast I get a head rush. I tell him I think most guys, him included, don't have the guts to Bang With Friends. He says he often has sex with women and then "lets them sleep over" to be polite. I say I've had enough of shitty, gray-area pseudorelationships like that (I want a boyfriend or a sex friend, nothing in between) and bolt for a taxi. As I'm crossing the Brooklyn Bridge, my cell phone vibrates: "When can I see you again?"—Elyse Moody

CASE STUDY 5:

She Discovered Another Kind of Intimacy

I matched with X on Tinder and eventually agreed to an in-person meet-up that proved completely devoid of chemistry or intimacy (crowded dive bar, friend entourages for each of us, forced conversation). Still, when he texted out of the blue a few weeks later—"Hey hey. Happy afternoon. What are you doing?" (an opener as boring and unoriginal as his face-to-face material)—I happily responded. My inner monologue went something like this: I'm sitting at my desk at 3 P.M. on a Wednesday debating whether the line will be longer at the Starbucks across the street or the one next door—what do I have to lose? Which is roughly the same logic that governed for the next three months as we engaged in on-and-off texting conversations about nothing in particular ("When is it going to stop snowing?") with an unspoken lack of motivation to ever meet again.

To be clear, this never became a virtual relationship of the Anthony Weiner sort. In fact, I think I'd have to fight to get it even a PG-13 rating. (The most racy it ever got? He mentioned once having gone on a date with a woman who lived in my friend's building. Me: "They have benches in the showers there." Him: "I never got to see the showers.") Steamy. But it did get weirdly intimate. Sometimes I'd find myself briefing him on quotidian details of my life—an assignment at work, an unpleasant trip to the dentist—that I never got around to telling my closest friends. When he'd ask if I ever resolved that problem with American Airlines/found my debit card/recovered from all that novocaine, I felt fleetingly known. I'd wonder if there were anyone else in the world who knew as much about me in that particular moment as this man, a practical stranger. Which began to disturb me, and probably explains why our communication gradually dwindled to nothing.

But I don't regret the interlude. I understand why studies have reported that texting can be as intoxicating as cocaine. I thrill a little at the telltale iPhone ding and long for it when too many minutes—forget hours—pass without it. Beyond that, I enjoyed the companionship X and I shared, circumscribed as it was. As for what he got out of it, I think much the same as I did. Then again, I honestly don't know him very well.—Amanda FitzSimons

CASE STUDY 6:

She Got Screwed—And Not in a Good Way

Last summer this guy who lived in L.A. but was in New York City for vacation began messaging me. It was a fun back-and-forth for a couple of days, a little flirty, then the messaging stopped suddenly. Eh, bummer. But pretty par for the course with Tinder. That Friday a friend invited me to a party in Brooklyn. As soon as I walk in, I spot Tinder dude. We get introduced and there's the mortifying "I think I know you from Tinder." We end up having a tiny, couple-day thing. He went back to L.A. and it all started. Texting. Instagram. Twitter. Facebook. We were connected in every way but emotionally. Six months later he's back in New York, we meet up for drinks, and he tells me dramatically that the rest of the visit he'll be too busy to hang out. I don't know if it was the three drinks or all the months of buildup, but I started crying. I stopped into a store, eyeliner running down my face, and the store manager comes over. "Whoever he is, he's not worth it," he says. "There's lots of good guys out there! You should try Tinder!"—As told to Molly Langmuir